Effects of lateral maneuvering on pectoral fin flow structures and forces

A robotic fish-like vehicle equipped with control surfaces inspired by the pectoral fins of fish is used to study the maneuverability of an underwater vehicle in the direction perpendicular to the swimming direction. The vehicle is equipped with two rigid flapping plates immersed in a water channel, and the flow is nominally two-dimensional. The forces produced by the pectoral fins are measured in real time, and a cyber-physical system is used to laterally move the vehicle in response to the lift forces generated by the flapping appendages. We perform time-resolved PIV for two cases: first, with a stationary vehicle and secondly, with the vehicle performing a lateral maneuver. Experiments are performed for a range of Reynolds and Strouhal numbers, and the impact of the lateral velocity on the instantaneous forces and flow structures are assessed.